This invention relates generally to an inclination angle adjusting mechanism, in an optical disk apparatus for data recording and reproduction on and from a CD (Compact Disc), DVD (Digital Versatile Disk) or the like, for adjusting the inclination of a spindle motor relative to a chassis so that a rotary shaft of the spindle motor lies parallel to an optical axis of an optical pickup. More specifically, the invention relates to such an inclination angle adjusting mechanism which allows independent adjustment of the inclination angle in a track-widthwise direction and a track-tangential direction and reduces the amount of movement of a turntable upon adjustment.
For storing information in an optical disk or reproducing the information from the optical disk, it is necessary for an optical axis of an optical pickup to pass perpendicularly to a storage surface of the optical disk. For this purpose, a rotary shaft of a spindle motor of an the optical disk apparatus and the optical axis of the optical pickup need to be arranged parallel to each other. However, due to a molding error and/or an assemblage error in a chassis of the optical disk apparatus, the rotary shaft of the spindle motor and optical axis of the optical pickup may be arranged somewhat offset from the desired parallel state. Therefore, an inclination angle adjusting mechanism is installed on the chassis so that after completion of assemblage, the spindle motor can be inclined relative to the chassis to thereby place the rotary shaft of the spindle motor parallel to the optical axis of the optical pickup. The inclination angle adjustment is carried out before shipping of the resulting product.
FIGS. 2A-2D hereof show a conventional inclination angle adjusting mechanism. A chassis 10 includes pedestals 12, 14 fixedly disposed thereon. The pedestals 12, 14 have inclined surfaces 12a, 14a on which a motor base 18 with a spindle motor fixedly disposed thereon is placed. Part 18c of the pedestal 18 abuts against an inclined cam surface 37a at an upper end of a cylindrical cam 37 rotatably attached to the chassis 10. A turntable 22 is mounted on a rotary shaft 20 of a spindle motor 16. Screws 24, 26, 28 pass through the motor base 18 and are threaded into the chassis 10. Around the screws 24, 26, 28, springs 31, 32, 33 are disposed in their compressed states such that their resilient forces press the motor base 18 against the pedestal inclined surfaces 12a, 14a and cam surface 37a. An eccentric cam 27 has an eccentric pin 29 which is engaged in a cam hole 30 of the motor base 18. By turning the eccentric cam 27 in a direction of arrow K with the eccentric pin 29 engaged in the cam hole 30, the motor base 18 is caused to move in a direction of arrow L while ends 18a, 18b of the motor base 18 slide along the inclined surfaces 12a, 14a of the pedestals 12, 14, thereby completing the adjustment of the inclination angle in one direction (track-tangential direction) of the spindle motor 16 relative to the chassis 10. At this time, the pins 25, 27 fixedly secured to the chassis 10 are engaged in recesses 18d, 18d of the motor base 18 thereby inhibiting sliding movement of the motor base 18 in a direction perpendicular to the rotary shaft 20 and to the arrow L. By turning the cylindrical cam 37 in a direction of arrow M, the motor base 18 rotates about an axis N or Nxe2x80x2 corresponding to its side portions placed in contact with the pedestal inclined surfaces 12, 14, thereby perfecting the adjustment of inclination angle in another direction (track-widthwise direction).
Japanese Patent Laid-Open Publication No. HEI-8-17135 shows another conventional inclination angle adjusting mechanism as illustrated in FIG. 3 hereof. A turntable 38 is mounted to a rotary shaft 36 of a spindle motor 35 which is fixedly disposed on a motor base 40. The motor base 40 is mounted to a chassis 41 at three points C, D and E. At point C, the motor base 40 and the chassis 41 are connected together through a screw 42 with a spacer 44 sandwiched therebetween, whereby the motor base 40 is rendered capable of tilt actions at point C as a fulcrum in all directions. At point D, the chassis 41 and the motor base 40 are connected together via a screw 48 with a spring 46 sandwiched therebetween. In correspondence with the amount of screwing of the screw 48, the inclination angle of the motor base 40 is adjusted, using line F passing over points C and E as a tilt movement axis, in a direction around line F. At point E, the chassis 41 and the motor base 40 are connected together via a screw 52 with a spring 50 sandwiched therebetween. In correspondence with the depth or amount of screwing of the screw 52, the inclination angle of the motor base 40 is adjusted, using line G passing over points C and D as a tilt movement axis, in a direction around line G.
Japanese Patent Laid-Open Publication No. HEI-9-223353 discloses a still another conventional inclination angle adjusting mechanism as illustrated in FIG. 4 hereof. A spindle motor 53 includes a rotary shaft 54 to which a turntable 56 is mounted. The spindle motor 53 is fixedly disposed on a motor base 58. The motor base 58 is supported by a chassis 60 tiltably in all directions at point H. At point I, the chassis 60 and the motor base 58 are connected together by means of a screw 64 with a spring 62 sandwiched therebetween. In correspondence with the depth of threaded engagement of the screw 64, the inclination angle of the motor base 58 is adjusted, using a line passing over points H and J as a tilt movement axis, in a direction around the line or tilt movement axis. At point J, the chassis 60 and the motor base 58 are connected together by means of a screw 68 with a spring 66 sandwiched therebetween. In correspondence with the depth of screwing of the screw 68, the inclination angle of the motor base 58 is adjusted, using a line passing over points H and I as a tilt movement axis, in a direction around the line.
In the conventional inclination angle adjusting mechanism shown in FIG. 2, the height of the turntable 22 is influenced by a bend position error in the end portions 18a, 18b of the motor base 18 and positional and angular errors in the pedestal inclined surfaces 12a, 14a, thereby making it difficult to ensure precision of the height of the turntable 22. These positional and angular errors also reflect upon the track-tangential-direction position of the turntable 22, thus causing the direction of movement of the optical axis by the feed action of the optical pickup to be offset from a direction normal to a central axis of the optical disk. In addition, since a central axis of the tilt action of the eccentric cam 27 is imaginary, difficulty is experienced in establishing the axis at one point clearly.
In the conventional inclination angle adjusting mechanism shown in FIG. 3, since the motor base 40 vertically swings about point C as the screws 48, 52 are turned, the turntable 38 vertically moves largely during inclination adjustment. There is therefore a problem such that focusing cannot be achieved where a displacement range of a focus actuator of the optical pickup is small. Further, as the screw 48 is turned, the motor base 40 tilts at the oblique tilt movement axis F passing over points C and E. This causes a tilt action to arise in both tangential and widthwise directions with respect to tracks of the optical disk, thus rendering the adjustment difficult to achieve.
In the conventional inclination adjusting mechanism shown in FIG. 4, since the motor base 58 vertically swings about point H as the screws 64, 68 are turned, the turntable 56 vertically moves largely. As a result, focusing cannot be achieved where a displacement range of a focus actuator of the optical pickup is small.
It is therefore an object of the present invention to provide a spindle motor inclination angle adjusting mechanism which allows inclination angle adjustment in track-widthwise and track-tangential directions independently and reduces the amount of movement of the turntable upon adjustment.
According to the present invention, there is provided a spindle motor inclination angle adjusting mechanism, in an optical disk apparatus including a spindle motor with a rotary shaft carrying a turntable thereon, a chassis supporting the spindle motor thereon, and an optical pickup disposed on the chassis transferably so that an optical axis of the optical pickup can be moved in a direction substantially perpendicular to the rotary shaft of the spindle motor, for adjusting inclination of the spindle motor relative to the chassis, which adjusting mechanism comprises: a tilt movement mechanism for supporting the spindle motor on the chassis tiltably both in a direction around a first tilt movement axis extending in a direction perpendicular to the rotary shaft of the spindle motor and perpendicular to a direction of movement of the optical axis of the optical pickup and in a direction around a second tilt movement axis extending in a direction of movement of the optical axis of the optical pickup and being perpendicular to the rotary shaft of the spindle motor; a first adjusting section for adjusting the inclination angle in the direction around the first tilt movement axis by driving the spindle motor in the direction around the first tilt movement axis; and a second adjusting section for adjusting the inclination angle in the direction around the second tilt movement axis by driving the spindle motor in the direction around the second tilt movement axis.
According to this invention, the spindle motor is supported on the chassis such that it can tilt in both the direction around the first tilt movement axis extending in the direction perpendicular to the rotary shaft of the spindle motor and perpendicular to the direction of movement of the optical axis of the optical pickup, and the direction around the second tilt movement axis perpendicular to the rotary shaft of the spindle motor and extending in the direction of movement of the optical axis of the optical pickup. The spindle motor is driven, by means of the first adjusting section, in the direction around the first tilt movement axis relative to the chassis to thereby effect the inclination angle adjustment in the direction around the first tilt movement axis. The spindle motor is also driven, by means of the second adjusting section, in the direction around the second tilt movement axis relative to the chassis to thereby effect the inclination angle adjustment in the direction around the second tilt movement axis. Accordingly, it becomes possible to effect the inclination angle adjustment in the direction around the first tilt movement axis and in the direction around the second tilt movement axis independently, thus rendering the adjustment operation easy. Further, since the second and first tilt movement axes are positioned to pass over the rotary shaft of the spindle motor, it becomes possible to reduce the amount of vertical movement of the turntable upon inclination angle adjustment such that focusing can be performed when the range of displacement of a focus actuator is small.
The tilt movement mechanism may have an arrangement wherein the spindle motor is supported on the motor base tiltably in the direction around the second tilt movement axis and the motor base is supported on the chassis tiltably in the direction around the first tilt movement axis.
The first and second adjusting sections may comprise an urging section for urging the spindle motor in the direction around the first and second tilt movement axes, a first pressing member for pressing the spindle motor back in the direction around the first tilt movement axis against the urging force of the urging aection to thereby adjust the inclination angle in the direction around the first tilt movement axis, and a second pressing member for pressing the spindle motor back in the direction around the second tilt movement axis against the urging force of the urging section to thereby adjust the inclination angle in the direction around the second tilt movement axis.
The urging section may comprise two separate urging sections, one for imparting an urging force in the direction around the first tilt movement axis and the other for imparting an urging force in the direction around the second tilt movement axis. In this instance, the urging section for imparting an urging force in the direction around the first tilt movement axis may be arranged to impart a pressing force to the spindle motor. It may also be arranged to impart a pressing force directly to the motor base.
The first tilt movement axis may be provided by an arrangement wherein the motor base is provided with extended portions of narrow width on opposite sides thereof with the rotary shaft interposed therebetween, and the extended portions have a direction of extension perpendicular to the direction of movement of the optical axis of the optical pickup and are supported on the chassis rotatably in a direction around an axis formed by the direction of extension.
In this instance, the extended portions of the motor base may be supported on the chassis with lower surfaces thereof placed on projections formed on the chassis and with upper surfaces thereof held in contact with projections of a leaf spring mounted on the chassis. The leaf spring projections may be positioned offset relative to the mecha-chassis projections so that they produce a moment which imparts to the motor base an urging force in the same direction as that of an urging force directed around the first tilt movement axis by the urging means.
The second tilt movement axis may be provided by an arrangement wherein protrusions are formed on opposite sides, interposing the rotary shaft of the spindle motor therebetween, of an end surface, opposed to the turntable, of an outer cylinder of the spindle motor, at positions along the second tilt movement axis, and the motor base is mounted on the protrusions in such a manner as to be tiltable in the direction around the second tilt movement axis about the protrusions forming a fulcrum.
The protrusions may be formed of metallic pins. In this instance, the second tilt movement axis may be established by providing an arrangement wherein the pins pass through the motor base to support the motor base tiltably about the metallic pins as a fulcrum and have upper parts having an increased diameter for preventing retrieval thereof from the motor base, and a spring is disposed between the outer cylinder end surface of the spindle motor and the motor base for urging the motor base against the increased diameter parts of the metallic pins such that the motor base becomes tiltable about the contact portion as a fulcrum.
The spindle motor inclination angle adjusting mechanism according to the present invention may be arranged such that the spindle motor is tiltably received in a sleeve disposed in the chassis and having an inner diameter larger than an outer diameter of the spindle motor, the urging section comprises a leaf spring mounted on the sleeve for pressing an outer cylinder side surface of the spindle motor to impart to the spindle motor an urging force in the directions around the first and second tilt movement axes, the first pressing member comprises a first screw extending in a direction parallel to the second tilt movement axis and perpendicular to the rotary shaft of the spindle motor, mounted on the sleeve and passing through the sleeve for pressing the outer cylinder side surface of the spindle motor in the direction around the first tilt movement axis, and the second pressing member comprises a second screw extending in a direction parallel to the first tilt movement axis and perpendicular to the rotary shaft of the spindle motor, mounted on the sleeve and passing through the sleeve for pressing the outer cylinder side surface of the spindle motor in the direction around the second tilt movement axis.